DES (diethylstilbestrol) has been shown, in studies of animals and on a small scale in humans to be associated with genitourinary abnormalities and possible reduced fertility in males exposed to the drug in utero. Human studies to date do not demonstrate an association with cancer in the DES-exposed male. However, preliminary reports of case control studies in progress have suggested such an association. Whether the exposed young men will have an increased propensity to develop cancer at a later date remains speculative. The proposed study is primarily designed to determine if DES-exposed males are at a higher risk of genitourinary problems or infertility than non-exposed males. This would be accomplished by identifying and examining a cohort of 300 DES-exposed and 300 non-exposed males and by a follow-up over a 2-year period. The DES-exposed males will be identified through the DESAD Project (the study of DES-exposed females) at Mayo Clinic. The young men will be examined for clinical abnormalities and variations in levels of FSH, LH and testosterone. It is expected that the study will give further information regarding the prevalence of abnormalities in DES-exposed males-information relating to the role of DES in teratogenesis and the public health aspects of the problem. Ultimately, this study should lead to greatly increased accuracy of assessment of the health status of the DES exposed men and to recommendations regarding their long-term surveillance (and health care, if needed).